1. Field of the Invention
The invention relates to protein- and/or peptide-based biomarkers useful for predicting, diagnosing, prognosticating and/or monitoring diseases and conditions in subjects, in particular renal dysfunction; and to related methods, kits and devices.
2. Background of the Invention
In many diseases and conditions, a favourable outcome of prophylactic and/or therapeutic treatments is strongly correlated with early and/or accurate prediction, diagnosis, prognosis and/or monitoring of a disease or condition. Therefore, there exists a continuous need for additional and preferably improved manners for early and/or accurate prediction, diagnosis, prognosis and/or monitoring of diseases and conditions to guide the treatment choices.
The mammalian renal system plays central roles inter alia in the removal of catabolic waste products from the bloodstream and in the maintenance of fluid and electrolyte balances in the body.
Renal dysfunction encompasses diseases and conditions in which kidney function is inadequate, such as for example diseases and conditions characterised by an acute or chronic deterioration of kidney function, more particularly characterised by an acute or chronic decline in kidney excretory function, as evidenced for example by reduced glomerular filtration rate. Renal dysfunction may develop into a life-threatening condition in which the (systemic) build-up of catabolic waste products and other harmful or toxic substances and/or the development of significant imbalances in bodily fluids or electrolytes may lead to, contribute to or exacerbate the failure of other major organ systems and death.
Signs and symptoms of renal dysfunction may include inter alia increased levels of urea in the blood, volume overload and swelling, abnormal acid levels, abnormal levels of potassium, calcium and/or phosphate, changes in urination, fatigue, skin rash or itching, nausea, dyspnea, reduced kidney size, haematuria and anaemia. However, renal dysfunction is frequently insidious and may progress to an advanced stage before the patient notices problems and decides to seek a physician. Therefore, renal dysfunction is commonly diagnosed late, and the patient may already be in need of radical and non-trivial treatments such as dialysis or kidney transplantation.
To aid diagnosis of renal dysfunction, some methods have been developed previously. For example, one way is to determine the glomerular filtration rate (GFR). However, GFR measurements rely on invasive, time-consuming and expensive procedures involving the injection of exogenous and potentially harmful diagnostic substances and measuring their excretion at specified time period(s). Another method is to measure serum creatinine clearance. Creatinine originates from muscle tissue and is increasingly secreted by renal tubules concomitant with decreasing renal function. However, serum creatinine levels depend on age, sex, diet, muscle mass, ethnic background, physical activity, disease, other manners of secretion, etc., which factors may impair the reliability of creatinine clearance for diagnosis of renal dysfunction. A further endogenous biomarker for diagnosing renal dysfunction is Cystatin C. Advantageously, compared to creatinine the expression of Cystatin C is comparably steady. Nevertheless, Cystatin C does show some limitations: for example, its levels are affected by immunosuppressive therapeutics and are dependent on thyroid function. Cystatin C also does not react rapidly enough to acute changes in GFR and is thus not a satisfactory marker for acute kidney injury (AKI). Another endogenous marker is neutrophil gelatinase-associated lipocalin (NGAL) which appears to detect early stages of acute renal injury. However, the use of NGAL is confounded by its anti-inflammatory role, which may lead to substandard specificity in complicated patient populations.
Furthermore, the timely (i.e. early) discovery of the need of renal replacement therapy (RRT) in postoperative or critically ill patients prone to develop kidney related problems is fundamental to reduce mortality. To date however there is no objective early measure for the need of RRT initiation and a biomarker that can specifically identify those patients that will benefit from early RRT is highly anticipated.
Dependable and preferably early detection and intervention is critical to effective treatment of renal dysfunction. Consequently, provision of further, alternative and preferably improved markers and tools for diagnosis, prediction, prognosis and/or monitoring of renal dysfunction continues to be of prime importance.
The present invention addresses the above needs in the art by identifying biomarkers for renal dysfunction and related diseases and conditions and providing uses therefore.